Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-25 05:32:00 +00:00
Code Issues Packages Projects Releases Wiki Activity

ext4: teach ext4_ext_find_extent() to free path on error

Browse Source 
Right now, there are a places where it is all to easy to leak memory
on an error path, via a usage like this:

	struct ext4_ext_path *path = NULL

	while (...) {
		...
		path = ext4_ext_find_extent(inode, block, path, 0);
		if (IS_ERR(path)) {
			/* oops, if path was non-NULL before the call to
			   ext4_ext_find_extent, we've leaked it!  :-(  */
			...
			return PTR_ERR(path);
		}
		...
	}

Unfortunately, there some code paths where we are doing the following
instead:

	path = ext4_ext_find_extent(inode, block, orig_path, 0);

and where it's important that we _not_ free orig_path in the case
where ext4_ext_find_extent() returns an error.

So change the function signature of ext4_ext_find_extent() so that it
takes a struct ext4_ext_path ** for its third argument, and by
default, on an error, it will free the struct ext4_ext_path, and then
zero out the struct ext4_ext_path * pointer.  In order to avoid
causing problems, we add a flag EXT4_EX_NOFREE_ON_ERR which causes
ext4_ext_find_extent() to use the original behavior of forcing the
caller to deal with freeing the original path pointer on the error
case.

The goal is to get rid of EXT4_EX_NOFREE_ON_ERR entirely, but this
allows for a gentle transition and makes the patches easier to verify.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2014-09-01 14:34:09 -04:00
parent bd30d702fc
commit 705912ca95
3 changed files with 21 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/ext4/ext4.h
View File

@ -582,6 +582,7 @@ enum {
*/
#define EXT4_EX_NOCACHE 0x0800
#define EXT4_EX_FORCE_CACHE 0x1000
#define EXT4_EX_NOFREE_ON_ERR 0x2000
/*
* Flags used by ext4_free_blocks
@ -2733,7 +2734,7 @@ extern int ext4_ext_insert_extent(handle_t *, struct inode *,
struct ext4_ext_path *,
struct ext4_extent *, int);
extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
struct ext4_ext_path *,
struct ext4_ext_path **,
int flags);
extern void ext4_ext_drop_refs(struct ext4_ext_path *);
extern int ext4_ext_check_inode(struct inode *inode);

28
fs/ext4/extents.c
View File

@ -855,11 +855,13 @@ int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
struct ext4_ext_path *
ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
struct ext4_ext_path *path, int flags)
struct ext4_ext_path **orig_path, int flags)
{
struct ext4_extent_header *eh;
struct buffer_head *bh;
short int depth, i, ppos = 0, alloc = 0;
struct ext4_ext_path *path = orig_path ? *orig_path : NULL;
short int depth, i, ppos = 0;
short free_on_err = (flags & EXT4_EX_NOFREE_ON_ERR) == 0;
int ret;
eh = ext_inode_hdr(inode);
@ -871,7 +873,7 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
GFP_NOFS);
if (unlikely(!path))
return ERR_PTR(-ENOMEM);
alloc = 1;
free_on_err = 1;
}
path[0].p_hdr = eh;
path[0].p_bh = NULL;
@ -923,8 +925,11 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
err:
ext4_ext_drop_refs(path);
if (alloc)
if (free_on_err) {
kfree(path);
if (orig_path)
*orig_path = NULL;
}
return ERR_PTR(ret);
}
@ -1356,7 +1361,7 @@ repeat:
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode,
(ext4_lblk_t)le32_to_cpu(newext->ee_block),
path, gb_flags);
&path, gb_flags | EXT4_EX_NOFREE_ON_ERR);
if (IS_ERR(path))
err = PTR_ERR(path);
} else {
@ -1369,7 +1374,7 @@ repeat:
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode,
(ext4_lblk_t)le32_to_cpu(newext->ee_block),
path, gb_flags);
&path, gb_flags | EXT4_EX_NOFREE_ON_ERR);
if (IS_ERR(path)) {
err = PTR_ERR(path);
goto out;
@ -2152,7 +2157,7 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
path = NULL;
}
path = ext4_ext_find_extent(inode, block, path, 0);
path = ext4_ext_find_extent(inode, block, &path, 0);
if (IS_ERR(path)) {
up_read(&EXT4_I(inode)->i_data_sem);
err = PTR_ERR(path);
@ -3313,7 +3318,8 @@ static int ext4_split_extent(handle_t *handle,
* result in split of original leaf or extent zeroout.
*/
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode, map->m_lblk, path, 0);
path = ext4_ext_find_extent(inode, map->m_lblk, &path,
EXT4_EX_NOFREE_ON_ERR);
if (IS_ERR(path))
return PTR_ERR(path);
depth = ext_depth(inode);
@ -3697,7 +3703,8 @@ static int ext4_convert_initialized_extents(handle_t *handle,
if (err < 0)
goto out;
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode, map->m_lblk, path, 0);
path = ext4_ext_find_extent(inode, map->m_lblk, &path,
EXT4_EX_NOFREE_ON_ERR);
if (IS_ERR(path)) {
err = PTR_ERR(path);
goto out;
@ -3769,7 +3776,8 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
if (err < 0)
goto out;
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode, map->m_lblk, path, 0);
path = ext4_ext_find_extent(inode, map->m_lblk, &path,
EXT4_EX_NOFREE_ON_ERR);
if (IS_ERR(path)) {
err = PTR_ERR(path);
goto out;

2
fs/ext4/move_extent.c
View File

@ -37,7 +37,7 @@ get_ext_path(struct inode *inode, ext4_lblk_t lblock,
int ret = 0;
struct ext4_ext_path *path;
path = ext4_ext_find_extent(inode, lblock, *orig_path, EXT4_EX_NOCACHE);
path = ext4_ext_find_extent(inode, lblock, orig_path, EXT4_EX_NOCACHE);
if (IS_ERR(path))
ret = PTR_ERR(path);
else if (path[ext_depth(inode)].p_ext == NULL)